Condenser and method of making the same



Sept. 11, 1923. 1,467,776

P. E. DEMMLER CONDENSER AND METHOD OF MAKING THE SAME Filed Jan. 16 1919WITNESSES: v INVENTOR A'TTORNEY ?atented Sept. 11, 1923.

PATENT @FFHQE.

PAUL E. DEMMLER, 0F PITTSBURGH, ll?Elbl'ltllbfiLVANIA, ASSIGNOB TOWESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 0FIEHNSYLVANIA.

CONDENSER AND METHOD GE MAKING THE SAME.

Application filed January 18, 1919.

To all wlrom it may concern:

Be it known that I", PAULE. DEMMLER, a citizen of the United States, anda resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Condensersand Methods of Making the Same, of which the following is aspecification.

My invention relates to condensers and to methods of makingthe'same andit has, for its'primary object, the construction of condensers by amethod which will insure a product ofcompact structure and highefficiency. V

It is well known that the efficiency of a condenser is increased as thedistance between the layers of conducting material embodied in thecondenseris decreased. It is very desirable, therefore, that adielectric be employed which will insure disposition of the layers ofconducting material of the condenser in as close relation as possible.In view of this, one object of my invention is to provide condensershaving a dielectric material which will insure compact disposition ofthe conducting material and, consequent-1y, a highly efficient product.

Another object of my invention is to con-.

struct condensers by a niethod which will promote rapid production ofsuch articlesand thus decrease the cost of them.

A still further'object of my invention is to construct condensers ofreadily available material which is comparatively inexpensive.

With these and other objects in view. my invention will be more fullydescribed, illustrated in 'the drawings, in the several views of whichcorresponding numerals indicate like parts, and then particularlypointed out in the claims.

In the drawings, Fig. l is an end elevation of an insulated metal "foilwhich may be employed in constructing a condenser in accordance with myinvention; Fig 2 is a diagrammatic view, illustrating a method offorming condensers'in accordance with my invention; Fig. 3 is a planview of a partially-formed condenser embodying n iy invention, and Fig.4 is an end .view. partly in elevation and partly in section. of afinished condenser constructed by a method hereinafter set forth. I mayconstruct a condenser, in accordance with my invention, by employingmetal foil ot-suitable width and length and sub- Serial No. 271,545.

jecting the metal foil to a bath of insulating adhesive adapted toharden under the application of heat. I employ a plurality of strips ofmetal foil, insulated as above mentioned, and wind these strips togetherso that they engage each other throughout the major portion of theirlengths to provide a condenser. The insulating'material, hardened on thestrips of metal foil, is utilized as the dielectric and the .foil as theconducting material, as in ordinary condensers. The ends of the metalfoil are disposed in spaced relation to provide (adequate insulationbetween the'inner ends and to allow fastening of terminals to the outerends.

In Fig. 1 is shown a metal foil or ribbon 1, coated with an insulatingor dielectric material 2, which may be employed in constructing acondenser. The foil 1 may be of substantially 280 (1., is closely unitedwith.

the varnish. I have found, however, in some instances, that it isdesirable to first pickle the aluminum foil in a hot hydro-' chloricacid bath which may comprise one part hydrochloric acid to substantiallythree parts of water. The aluminum foil may then be-washed in water anddried. The

foil may also be washed in naphtha or benzol, without any pickling. Suchtreatment ensures unusually good adhesion between the baking varnish andthe foil.

Various materials may be employed in making a foil for use inconstructing condensers in accordance with my invention. For example, afoil comprising substantially 85% lead and 15% tin may be employed toget satisfactory results. However, some materials ensure better adhesionbetween the baking varnish and the toil and I have found that analuminum foil gives slightly better results, in this respect, than afoil comprising lead and tin, in the above mentioned proportions.

I may employ a plurality of strips of aluminum foil coated with bakingvarnish and wind these strips to form a condenser.

The method of winding the strips is best illustrated in Fig. 2. As hereshown, a plurality of plates 3 of insulating material, such as micarta,may be employed. The micarta com rises merely a layer or two of paper ormus in impregnated with a hardened phenolic condensation product.However,

any kind of suitable insulating plate may be employed. Strips 4 of foilmay be wound about such plates 3 by first disposing one end of eachstrip 4 between the plates, the ends being in spaced relation so thatthey will be insulated from each other. This is done for the reason thatthe varnish adheres less strongly to the edges of the foil when it issubjected to the coating) process and, therefore, it is more likely toreak down at these edges. After the ends of the foils are disposedbetween the plates, the plates ma be forced together, as near aspossible an the windings of the foil disposed about them as indicated inFig. 2.

On account of the fact that the baking varnish or other insulatingmaterial adheres less strongly to the edges of the foil, it isadvantageous to employ strips of foil of different widths. I haveillustrated in Fig. 3, a condenser 5 formed of a plurality of oils ofdifierent widths. The broken line 6 indicates the edge of the narrowstrip of foil 7. Furthermore, by employing a plurality of foils ofdifferent widths, one of the foils may be utilized without being coated.In {this case, the wider coil is coated.

As shown in Fig. 4, the foils 8 and 9 are wound upon insulating plates10 and 11 so as to engage each other throughout the major portion oftheir lengths, the inner and outer ends being disposed in spacedrelation. The inner ends, as above mentioned, are disposed in spacedrelation to provide adequate insulation between them and the outer endsare so disposed to provide insulation as well as to faciliate securingterminals 12 and 13 to the respective foils. However the foils may beWound, they may be subjected to treatment in a bath of a suitable moltenwax v to expel the air. After the spaces are filled rial. Furthermore,by constructing a condenser of continuous windings and b employing afilm possessing a high die 'ectric strength, the ultimate condenser maybe made very compact and thus ensure efficient service. Furthermore, theinsulating film or dielectric, being very tough, supplements thestrength of the foil and increases the durability of the finishedcondenser.

Although I have specifically described a method by which condensers maybe constructed in accordance with my invention and specified materialswhich may be employed, it is obvious that various materials and methodsof employing them may be utilized within the scope of my invention and Idesire, therefore, that no limitations shall be imposed except such asare indicated in the appended claims.

I claim as my invention 1. A condenser comprising windings of aplurality of metallic ribbons, one of which is of greater width than theother and a coating of hardened baking varnish disposed on the widerribbon.

2. A condenser comprising a plurality of plates of insulating materialand a plurality of metallic ribbons, one of which is coated with ahardened varnish, wound about'the insulating plates with their innerends maintained in spaced relation between the plates,

comprises coating a strip ofmetal foil with I varnish, drying thevarnish and winding the coated strip of foil, together with an uncoatedstrip, about a lurality of plates of insulating material with the innerends of the foils disposed in spaced relation between the plates.

In testimony whereof, I have hereunto subscribed my name this 31st dayof Dec., 1918.

PAUL E. DEMMLER.

